Bitumen froth treatment plants historically have been designed for a given froth feed flow despite the fact that the actual flow varies significantly in response to oil sand grade variation and upstream equipment availability. Variations in feed flow, composition and temperature can result in several challenges that affect recovery and unit reliability.
Conventional solutions to variable froth flow are to coordinate start up and shut down of froth treatment operations with upstream unit operations.
In addition to the significant coordination effort related to the displacement of oil sand to ore preparation sites as well as the logistics of supplying utilities for ore preparation, bitumen extraction and tailings disposal, there are significant time delays associated with obtaining stability for each unit operation. An upset in any one unit can directly impact the production chain.
Oil sand operations are characterized by oil sand grade variations. The grade variations of the oil sand ore often range between approximately 7 wt % and 15 wt % bitumen, which is typically blended in mine and preparation operations to a narrower range between approximately 10.5 wt % and 12 wt %. This blending is dependant on equipment availability.
For some previous naphthenic froth treatment operations, dilution centrifuges were provided in parallel, the on/off operation of which permitted a range of process turndown options to adjust to froth supply variations. However, in paraffinic froth treatment operations, the large separation vessels that are used are sensitive to feed variations and upsets can interrupt efficiency of the production chain.
There is a need for a technology that overcomes at least some of the disadvantages or inefficiencies of known techniques.